Many sites do this, and so should this one. Put a link at the top of each article that says "Print this" or "Printer-friendly format" or "Hand me that piano" or something that takes you to a plain HTML version of the document only: no graphics, no borders, no sidebars, no other articles, just the article you're trying to print.

Should be simple, really. Take a look at Baseball Prospectus or the ABJ for examples.